Meningiomas are amongst the most commonly encountered intracranial and spinal cord associated tumors. While the majority of these tumors are clinically benign, a proportion of them develop into highly aggressive malignant neoplasms. While active efforts are being directed towards the cloning and identification of the "meningioma initiating locus" on chromosome 22, the molecular basis of the progression to malignancy of meningiomas is unknown and the histopathological grading of these tumors often controversial. The major objective of this study will be to use cytogenetics and highly polymorphic DNA markers to detect loss of heterozygosity in different grades of meningiomas, and thereby correlate tumor histopathology with specific molecular events in the DNA of these tumors. The identification f such chromosomal regions will set the stage for future studies in which the genes that are involved in tumor progression can be identified and cloned.